A display panel in a thin film transistor liquid crystal display device comprises a plurality of pixel units, each having at least three sub pixels including a red sub pixel, a green sub pixel and a blue sub pixel. The brightness of each sub pixel is determined by a gamma voltage.
The gamma voltage is provided by a gamma voltage driver circuit based on a gamma curve required by the liquid crystal display device, and acts as a reference voltage for gray scale display of the thin film transistor liquid crystal display device. Gamma voltages each are inputted to a source driver of the thin film transistor liquid crystal display device, and generate all the gray scale voltages through a digital to analog converter in the source driver circuit.
It is found that the existing gamma voltage driver circuit comprises a plurality of digital to analog converters (DACs) and a plurality of operational amplifiers (OPs), with each DAC being connected to a corresponding OP. The DAC converts a digital signal received for generating a pixel gray scale reference voltage into an analog signal, and the OP amplifies and transforms the analog signal processed by the DAC into a pixel gray scale reference voltage, and outputs the pixel gray scale reference voltage to the source driver circuit. Due to large voltage difference between both ends of the OP, both the power consumption and heat generating efficiency of the OP are high, rendering a temperature build-up of the gamma voltage driver circuit. Consequently, the gamma voltage driver circuit is difficult to be integrated with other driver circuits.